Carbon moves from living things to the atmosphere. Each time you exhale, you are releasing carbon dioxide gas (CO2) into the atmosphere. Animals and plants need to get rid of carbon dioxide gas through a process called respiration. Carbon moves from fossil fuels to the atmosphere when fuels are burned.
Tissue damage activates nociceptors or pain receptors in the skin. A signal is sent to the peripheral nerve to the spinal cord where neurotransmitters or chemical messengers are released. It activates other nerves to pass signal to the brain. The signals are relayed to the somatosensory cortex for sensation, frontal cortex for thinking and limbic system for emotional response.
Palisade mesophyll cells are closely packed to absorb the maximum light. They are at right angles to the surface of leaf to reduce the number of cross walls. Large vacuole pushes chloroplasts to the edge of a cell. Chloroplasts at edge enable short diffusion path for carbon dioxide and to absorb maximum light.
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<span>"G2 phase is the third, final, and usually the shortest subphase during interphase within the cell cycle in which the cell undergoes a period of rapid growth to prepare for mitosis. It follows successful completion of DNA synthesis and chromosomal replication during the S phase, and occurs during a period of often four to five hours. This far into interphase the nucleus is well defined, bound by a nuclear envelope and contains at least one nucleolus. Although chromosomes have been replicated they cannot yet be distinguished individually because they are still in the form of loosely packed chromatin fibers. The G2 phase prepares the cell for mitosis (M phase) which is initiated by prophase.
At the end of this gap phase is a control checkpoint (G2 checkpoint) to determine if the cell can proceed to enter M phase and divide. The G2 checkpoint prevents cells from entering mitosis with DNA damaged since the last division, providing an opportunity for DNA repair and stopping the proliferation of damaged cells. Because the G2 checkpoint helps to maintain genomic stability, it is an important focus in understanding the molecular causes of cancer."</span>
